Friday, January 25, 2008

Alexander the Great’s conquests, and later the Roman Empire’s expansion, transformed the cultural landscape by merging different peoples into a syncretic Greco-Roman culture. Religion too became universal through the Hellenization of non-Greek deities and ultimately the emergence of a single universal faith. Within this same context, local markets dissolved into a larger market that brought supply and demand together throughout the Mediterranean, and even beyond.

These broadening horizons affected slave markets as well. Slaves were initially taken in war or carried off by pirates. With the suppression of piracy after the battle of Actium (31 BC) and the stabilization of the empire’s borders under the emperor Hadrian (117-138 AD), people turned to other sources: condemned criminals, children sold by indebted parents, foreigners purchased from outside the Empire (Westermann, 1955, pp. 84-85). The last source supplied nearly one eighth of all slaves, including some from sub-Saharan Africa by way of Egypt (Westermann, 1955, pp. 96, 135).

How many? Although it is known that some black Africans were present in the ancient Mediterranean world, the magnitude of their presence is hard to quantify. It is widely believed, notably by the historian Bernard Lewis, that they were relatively few in number until the creation of the Muslim world in the 7th century, when the black slave trade presumably took off (Lewis, 1990, p. 41). But there are reasons for believing that their numbers had grown considerably even before Islam, having increased slowly but steadily throughout the early Christian era. During that era, 4% of people buried in Corinth seem to have been black African (Angel, 1972). In the Egyptian scenes of the Ashburnham Pentateuch (6th century AD), almost a quarter of the faces are black. Finally, early Christian literature often mentions Ethiopians, as black Africans were called in Greek and Latin. Many of these mentions indicate personal familiarity.

Meanwhile, pagan, Christian, and Jewish writings increasingly associated dark skin with slavery. In the 1st century, the Roman author, Petronius, represents very light skin by Gauls and very dark skin by Ethiopian slaves (Satyricon 102). In the 2nd century, the Greek satirist, Lucian, wrote: “In the first place, is he not generous in his proportions and pleasing in his complexion, neither dark nor fair of skin; for the one befits a woman, and the other a slave (De parasito 41).

This mental association intensified during the early Christian era. It is especially attested by the tendency from the 3rd to 5th centuries to reinterpret the ‘Curse of Ham’ in the book of Genesis. This is the original version: when Ham saw his father Noah naked and drunk, Noah angrily condemned to slavery all of Ham’s descendents through Ham’s son, Canaan (Genesis 9: 22-27). Initially, the curse served to justify enslavement of the former inhabitants of the land of Israel, the Canaanites. Then, during the first centuries of the Christian era, it tended to target the brown- and black-skinned peoples of Africa—Ham’s supposed descendents. Finally, it came to hang solely over the black Africans, who were said to be descended from another of Ham’s sons, Chusi, but also more generally from Ham or even from Canaan.

Thus, in the 3rd century, St. Origen invoked the Curse of Ham to explain the servility of the “discolored” Egyptians:

Pharaoh easily reduced the Egyptian people to servitude, nor is it written that he did so by force. For the Egyptians are prone to a degenerate life and quickly sink to every slavery of the vices. Look at their origin: you will discover that their father Ham, who had laughed at his father’s nakedness, deserved a judgment of this kind, that his son Canaan should be a servant to his brothers, so that his condition of servitude would testify to the wickedness of his conduct. Not without reason, therefore, does the discolored posterity imitate the ignobility of the race. (Hom. in Genesim 16.1)

Dark skin is explicitly attributed to this curse in a 3rd or 4th century Samaritan exegesis: “When Kush saw the nakedness of his father, he was cursed and he wore darkness—he and all his descendents forever” (Goldenberg, 2003, p. 100). Similarly, according to a 4th century Christian account, attributed to St. Ephrem of Nisibis (Syria), Noah said: “Accursed be Canaan, and may God make his face black” (Lewis, 1990, p. 124). Another work attributed to St. Ephrem, The Cave of Treasures, also seems to link this curse to dark-skinned peoples:

For by means of singing, and lewd play, and the mad lasciviousness of the children of Cain, Satan had cast down the mighty men, the "sons of God," into fornication. And through the music of reed pipes and harps sin had multiplied among the former generations until, at length, God became wroth and made the Flood. And Canaan was cursed because he had dared to do this, and his seed became a servant of servants, that is to say, to the Egyptians, and the Cushites, and the Mûsâyê (Mysians), [and the Indians, and all the Ethiopians, whose skins are black]. And because Ham had dared to make a mock of his father he was called "vile" (or "lascivious") all the days of his life. (Ephrem, 1927, fol. 19a, 19b)

Two late versions (8th century) add: “and other blacks” or “and all those whose skin color is black” (Goldenberg, 2003, p. 173). These peoples are thus seen as having especially dark skin, i.e., darker than that of early Christians in the Greco-Roman world.

The Egyptians hold first place in this list, probably because they were the best known “people of color” at that time. Thus, the Greco-Roman world tended to see them as encompassing Ethiopians, i.e., black Africans, viewing the latter as Egyptians with even darker skin. This tendency to lump the two peoples together also appears in ancient rabbinic literature, which states that Egypt and Kush (Nubia and more generally sub-Saharan Africa) are the lands of “dark men” and that Egypt is “a place of ugly and dark people” (Goldenberg, 2003, p. 107-109, 117-118). According to the historian David Goldenberg (2003, p. 109): “Both the Jewish and the Greek etiologies show that in regard to skin color, the Kushites/Ethiopians were not considered in a separate category but were seen as part of a larger class of dark-skinned peoples.” It is in this broader sense that the word Egyptian seems to be used further on in The Cave of Treasures:

Now the seed of Canaan, as I have already said, are the Egyptians, and behold, they are scattered over the whole earth, and have been made servants of servants. And of what kind is this slavery of slavery? Behold, the Egyptians go round about all over the earth carrying loads on their backs (literally, necks). Now, men who are not fettered under the yoke of slavery, when despatched by their masters on journeys, do not march on their feet and carry loads, but they ride upon beasts in an honourable manner, like their masters. The seed of Ham are the Egyptians who carry loads, and they march on the roads with their backs and necks breaking under their loads, and they wander round to the doors of the children of their brethren. The seed of Ham was reduced, through the folly of Canaan, to suffer this penalty, that is, to become servants even to servants. (Ephrem, 1927, fol. 19b, 20a)

These “Egyptians” were probably black Africans. If so, this passage would testify, three centuries before Islam, to a sizeable diaspora of black slaves in the ancient world. In addition, these slaves were considered to be different from other slaves. This view is attested a century earlier when Origen wrote:

Thus, the divine laws provided that whoever has bought a Hebrew servant will not keep him indefinitely in servitude: he will serve six years and, the seventh, will go free. Nothing similar is decreed for the Egyptians: nowhere does the divine law have a provision for the freedom of the Egyptians, for they lost it willingly, and it abandons them to the eternal yoke of their fate and to perpetual servitude (Hom. in Genesim 16.1)

The Curse of Ham was similarly transformed in post-biblical Jewish literature. According to a 5th century text, Ham wished to keep his share of the inheritance intact and, to this end, tried to prevent his father from having another son. One day, seeing his father drunk and undressed, he seized the opportunity and castrated him. Noah awoke from his stupor and cursed Ham: “You have prevented me from doing something in the dark [i.e., sex], therefore your seed will be ugly and dark-skinned.” (Genesis Rabba 36:7). According to two Talmudic accounts from the 4th and 6th centuries, Ham violated a rule prohibiting sexual intercourse in Noah’s ark. Persuaded that the first child born after the flood would inherit the world, Ham defied the prohibition and copulated with his wife, whereupon his skin turned black (Tractate Sanhedrin 108b, Tractate Ta’an 1.6, 64d).

In the 6th century, a Christian philosopher from Alexandria, John Philoponus, named solely the black Africans as a people destined for slavery: “The Scythians and Ethiopians are distinguished from each other by black and white color, or by long and snubbed nose, or by slave and master, by ruler and ruled”; “The Ethiopian and Scythian … one is black, the other white; similarly slave and master” (Goldenberg, 2003, p. 135).

If at that time the Greco-Roman world already associated black skin with slavery, it is not because the slaves were almost all blacks but because the blacks were almost all slaves; this was the status of most foreigners. Indeed, it is precisely because black Africans formed a small visible minority that their servile status was easy to recognize (Goldenberg, 2003, pp. 135-136, 138). Furthermore, as Origen noted, they tended to retain this status longer, if not for life, thereby strengthening the mental association between dark skin and slavery.

It remains to be explained why this slave population became so numerically important even before the Islamic era. What was stimulating its growth? Perhaps supply and demand were reciprocally stimulating each other: since black Africans were less likely to lose their slave status, people increasingly came to see their tasks as “slave work” —unworthy of free people and treated accordingly. The supply thus favored its own demand by degrading the working conditions.

Friday, January 18, 2008

About 15 years ago, I received an e-mail from a specialist in Jewish studies, Dr. David Goldenberg, who had read an article of mine and wanted to know more about the subject. The article described how early Christians perceived Black Africans, or Ethiopians as they were then called, especially those who lived as a small visible minority in the Mediterranean world. I had come to this subject out of a desire to understand how differences in skin color were perceived in contexts that preceded the historical experiences of European colonialism and black slavery. This desire led me to such culture areas as the Mediterranean world of Late Antiquity, ancient India, and the contact zone between Melanesia and Polynesia. Ultimately, I wanted to isolate the patterns of perception and response that existed during the long period of human existence when, in any given society, skin color differed primarily between men and women.

David Goldenberg came to this subject from a very different angle. A number of African American authors were arguing that the Jews had invented anti-black racism, the “proof” being early rabbinical writings that had reinterpreted the Curse of Ham (originally pronounced on the Canaanites) as applying to the dark-skinned peoples of Africa. These writings certainly did exist. My article, however, showed that they were part of a larger Mediterranean tradition of attitudes to skin color that had originated as much with early Christians as with Jews.

For David, the situation was all the more worrisome because many Black Muslims were taking up the argument that “the Jews did it.” Ironically, this early Christian/Jewish ‘colorism’ had not disappeared from the Middle East with the rise of Islam; the Muslim world preserved it virtually intact, including the notion that God had condemned Black Africans to slavery and had blackened their skin as a mark of shame.

I provided him with more references, including other articles I had written. God knows what he thought of my other articles. Even fellow anthropologists think they’re weird—“But what does that have to do with racism?”

Some years after, in 2003, David Goldenberg came out with a book that pulls together all of his research: The Curse of Ham. Race and Slavery in Early Judaism, Christianity, and Islam. I have only just now started reading it and truly regret not having done so sooner. It provides a lot of material I was not aware of and is by far the most authoritative work on the subject. As such, it forms a companion piece to Bernard Lewis’ Race and Slavery in the Middle East.

Today, people routinely interpret antipathy to dark skin as being racially based. Dr. Goldenberg rises above this simplism, arguing that attitudes to skin color were much more fluid and less ethnically constructed in the ancient world. At that time, they were still largely aesthetic in nature and centered on the individual. It was only later, with the expansion of European societies into the non-European world, that these attitudes became almost wholly racialized and, as such, assumed a preponderant role in the modern worldview.

In short, what we call ‘racism’ did not develop historically from a blank slate. It arose from a transformation of earlier sentiments that were unrelated to race or ethnicity. This earlier pre-racial world is now half-forgotten, if not forgotten entirely.

As The Curse of Ham concludes on its last page:

Yet, what struck me as I read through hundreds of modern biblical commentaries and historical and cultural studies of ancient Judaism was how strongly the perspective of one’s own time and place shapes one’s view of another time and place. We today are heirs to centuries of anti-Black sentiment, which has greatly conditioned our perspective.(Goldenberg, 2003, p. 200)

References

Frost, P. (1991). Attitudes towards Blacks in the early Christian era, The Second Century, 8(1), 1-11.

Friday, January 11, 2008

2. If we look at the 0.1% that does vary, 85% of this variation exists only between individuals and not between populations.

Both truisms are at best superficially true. They don’t mean what many seem to think they mean. Moreover, they’ve been known to be misleading for some time; in the case of truism #1, from the moment it was first presented.

So Mr. Smarty Pants, how much do genes really differ within our species? And how much of this difference clusters into recognizable populations?

I don’t know. The problem is not simply lack of information. We’re dealing with a conceptual, even existential, problem. Genes differ in any number of ways—not only in the timing and magnitude of a particular trait, but also in countless qualitative aspects. If genes vary along a multitude of dimensions, how can we compress this multidimensional reality into one yardstick called “human difference”?

Let’s assume, as I suspect, that 10-15% of the human genome exhibits some variability. Can we say that humans differ by 10-15% from each other? I’m not so sure. For one thing, a lot of this variability is confined to remote, isolated populations that are close to extinction. Their variability is irrelevant to the overwhelming majority of humans.

For another thing, much of this variability has little or no selective value. How relevant are blood types to your daily existence? What about dormant DNA that might reactivate in one of your descendants?

Well, let’s stick to the 7% of the human genome that clearly varies because it has been selected differently in different environments (Hawks et al., 2007). How relevant are those selection pressures now? What’s the point of having a beard if you shave it off every day? And how important are hair and eye color? At one time, these color traits were under intense selection. Do they matter to us today? I suspect most people would say ‘no’ if asked. They would probably affirm that only ‘inner qualities’ matter, i.e., the soul, personality, intelligence, etc. Yet this viewpoint might change once they’re in a drugstore, especially the hair products section or the magazine counter …

Well, let’s stick to inner qualities. How do we weigh their relative importance? For instance, about 30 per cent of people have a gene variant that results in fewer dopamine receptors and, apparently, in stubborn behavior (Hall, 2008). How useful is this quality? For someone like Winston Churchill, it could have made the difference between losing and winning the war. For many elderly people, it might lead them to refuse ‘newfangled’ medication.

It’s hard to compare things that vary in value not only from one person to another but also from one situation to another. Ultimately, the single yardstick is survival and reproduction: does this trait help its bearer to survive and have children? If this is to be our yardstick, we must conclude that some people are ‘superior’ even though their behavior is widely deemed to be inferior, if not pathological. As anthropologist Henry Harpending points out:

Evolution is a double-edged sword. What evolution cares about is that I have more offspring. If you can do it by charming and manipulating, and I'm a hardworking farmer that's going to feed the kids ten years down the road, then you're going to win. Hit-and-run, irresponsible males are reproducing more. That isn't good for anyone except those males, but that's evolution. (Keim, 2007).

Friday, January 4, 2008

How much of the genome varies within our species? The question remained unanswered in my last post. Hawks et al (2007) have recently estimated that at least 7% of our genome has changed over the last 40,000 years—a period that has seen humans move into diverse environments with different selection pressures. Yet this is a minimal estimate that excludes much variation that may or may not be due to natural selection. The real figure could be higher. Much higher.

How is this genetic variation distributed among humans? Is it evenly scattered? Or does it form geographic clusters? Intuitively, the second answer seems more correct: This variation should be very unevenly distributed if it is due to humans settling in diverse environments with different selection pressures. It should occur primarily at the transition from one ecological zone to another or from one cultural zone to another (e.g., from agriculturalists to hunter-gatherers).

Yet this is not what we see in the data. If we look at genetic markers (blood types, serum proteins, enzymes, etc.), we consistently find far more variation within human populations than between them. And this is true not only for large ‘continental’ groups but also for smaller local populations. In a landmark paper, Richard Lewontin (1972, p. 397) concluded that 85% of human genetic variation exists only between individuals and not between populations:

It is clear that our perception of relatively large differences between human races and subgroups, as compared to the variation within these groups, is indeed a biased perception and that, based on randomly chosen genetic differences, human races and populations are remarkably similar to each other, with the largest part by far of human variation being accounted for by the differences between individuals.

This finding is true. Like many findings, however, it does not necessarily mean what we think it means. This became apparent when geneticists looked at genetic markers in other animals, such as dogs:

… genetic and biochemical methods … have shown domestic dogs to be virtually identical in many respects to other members of the genus. … Greater mtDNA differences appeared within the single breeds of Doberman pinscher or poodle than between dogs and wolves. Eighteen breeds, which included dachshunds, dingoes, and Great Danes, shared a common haplotype and were no closer to wolves than poodles and bulldogs. These data make wolves resemble another breed of dog.

… there is less mtDNA difference between dogs, wolves, and coyotes than there is between the various ethnic groups of human beings, which are recognized as a single species. (Coppinger & Schneider, 1995)

One could object that humans have created dog breeds using a limited set of criteria that reflect a limited set of genes. Therefore, all other criteria, especially those not visible to the eye, should vary independently of breed. The category ‘breed’ is thus an artificial construct that human selection, and not natural selection, has imposed on canine genetic variability.

This objection is not wholly true. Many breeds, such as dingoes, originated in prehistory long before kennel clubs. More to the point, if one argues that human selection acts on a limited set of genes, the implication is that natural selection acts on the entire genome. It doesn’t. Natural selection also acts on a limited set of genes, often a larger set than the one used by dog breeders, but still much smaller than the entire genome.

This point can be illustrated with non-canine examples. Considerable genetic overlap exists not only between breeds of dogs but also between many anatomically and behaviorally distinct species. In the deer family, genetic variability is greater within some species than between some genera (Cronin, 1991). Some masked shrew populations are genetically closer to prairie shrews than they are to other masked shrews (Stewart et al., 1993). Only a minority of mallards cluster together on an mtDNA tree, the rest being scattered among black ducks (Avise et al., 1990). All six species of Darwin’s ground finches seem to form a genetically homogeneous genus with very little concordance between mtDNA, nuclear DNA, and morphology (Freeland & Boag, 1999). In terms of genetic distance, redpoll finches from the same species are not significantly closer to each other than redpolls from different species (Seutin et al., 1995). Among the haplochromine cichlids of Lake Victoria, it is extremely difficult to find interspecies differences in either nuclear or mitochondrial genes, even though these fishes are well differentiated morphologically and behaviorally (Klein et al., 1998). Neither mtDNA nor allozyme alleles can distinguish the various species of Lycaedis butterflies, despite clear differences in morphology (Nice & Shapiro, 1999). An extreme example is a dog tumor that has developed the ability to spread to other dogs through sexual contact: canine transmissible venereal sarcoma (CTVS). It looks and acts like an infectious microbe, yet its genes would show it to be a canid and, conceivably, some beagles may be genetically more similar to it than they are to Great Danes (Cochran, 2001; Yang, 1996).

Does this seem paradoxical? Let’s review how organisms become different from each other through natural selection. This typically happens when a group buds off from its parent population and colonizes a new environment. The environment may be another ecosystem, another mode of subsistence or even, as with CTVS, another form of existence. As the group adapts to its new environment, it will begin to diverge anatomically and behaviorally from its parent population, in part because the environmental boundary hinders gene flow between them but more importantly because the pressures of natural selection are no longer the same. The two populations will evolve differently because what is useful in one environment may not be in the other. And vice versa.

Will these differences in selection affect the entire genome? No. For one thing, most genes have low selective value, some being little more than junk DNA. For another, many genes code for traits that are equally useful in a wide range of environments. The ‘building block’ proteins of human flesh and blood are largely identical to those of non-human primates and sometimes even non-primate mammals (King & Wilson, 1975).

Thus, only a fraction of the genome changes when one population differentiates from another in response to differences in natural selection. The rest remains unchanged, either because the genes have little selective value or because they handle adaptive problems that are common to both populations. Over most of the genome, then, variability is due not to adaptive differences created by different selection pressures but rather to non-adaptive variations that similar selection pressures have left in place.

Of course, once the two populations have become reproductively isolated, they will no longer accumulate the same non-adaptive variations and their entire genomes will drift steadily apart. But this takes time. Redpoll finches diverged into two species some 50,000 years ago and have distinct phenotypes, yet their mitochondrial DNA reveals a single undifferentiated gene pool (Seutin et al., 1995). It’s no surprise, then, that human populations exhibit so much genetic overlap. They began to move apart only 40,000 or so years ago (Pritchard et al., 1999).

Welcome to my blog! For the most part, this page will be an extension of my website, with comments relating to my research. But it will also branch out into more general discussions of human evolution.